Method and Apparatus for Tissue Ablation

ABSTRACT

The present invention is directed toward a device that performs ablation of tissue. The device has a catheter with a shaft through which an ablative agent can travel, a first positioning element attached to the catheter shaft at a first position and a second positioning element attached to the catheter shaft at a second position. The shaft also has ports through which the ablative agent can be released.

CROSS-REFERENCE

The present invention relies on U.S. Provisional Application No.61/102,885, filed on Oct. 6, 2008, for priority and is herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to medical apparatus and procedures. Moreparticularly, the present invention relates to a device for ablation oftissue in a hollow organ comprising a centering or positioningattachment in order to position the device at a consistent distance fromthe tissue to be ablated.

BACKGROUND OF THE INVENTION

Colon polyps affect almost 25% of the population over the age of 50.While most polyps are detected on colonoscopy and easily removed using asnare, flat sessile polyps are hard to remove using the snare techniqueand carry a high risk of complications, such as bleeding andperforation. Recently, with improvement in imaging techniques, more flatpolyps are being detected. Endoscopically unresectable polyps requiresurgical removal. Most colon cancer arises from colon polyps and, safeand complete resection of these polyps is imperative for the preventionof colon cancer.

Barrett esophagus is a precancerous condition effecting 10-14% of USpopulation with gastro esophageal reflux disease (GERD) and is theproven precursor lesion of esophageal adenocarcinoma, the fastest risingcancer in the developed nations. The incidence of the cancer has risenover 6 fold in the last 2 decades and mortality has risen by 7 fold. The5-year mortality from esophageal cancer is 85%. Ablation of Barrettepithelium has shown to prevent its progression to esophageal cancer.

Dysfunctional uterine bleeding (DUB), or menorrhagia, affects 30% ofwomen in reproductive age. These symptoms have considerable impact on awoman's health and quality of life. The condition is typically treatedwith endometrial ablation or a hysterectomy. The rates of surgicalintervention in these women are high. Almost 30% of women in US willundergo hysterectomy by the age 60, with menorrhagia or DUB being thecause for surgery in 50-70% of these women. Endometrial ablationtechniques have been FDA approved for women with abnormal uterinebleeding and with intramural fibroids less than 2 cm. The presence ofsubmucosal uterine fibroids and a large uterus size have been shown todecrease the efficacy of standard endometrial ablation. Of the five FDAapproved global ablation devices (namely, Thermachoice, hydrothermalablation, Novasure, Her Option, and microwave ablation) only microwaveablation (MEA) has been approved for use where the submucosal fibroidsare less than 3 cm and are not occluding the endometrial cavity and,additionally, for large uteri up to 14 cm.

The known ablation treatments for Barrett esophagus include lasertreatment (Ertan et al, Am. J. Gastro., 90:2201-2203 [1995]), ultrasonicablation (Bremner et al, Gastro. Endo., 43:6 [1996]), photodynamictherapy (PDT) using photo-sensitizer drugs (Overholt et al, Semin. Surq.Oncol., 1:372-376 (1995), multipolar electrocoagulation such as by useof a bicap probe (Sampliner et al,), Argon Plasma Coagulation (APC;),Radiofrequency ablation (Sharma et al. Gastrointest Endosc) andcryoablation (Johnston et al. Gastrointest Endosc). The treatments aredelivered with the aid of an endoscope and devices passed through thechannel of endoscope or alongside the endoscope.

Conventional techniques have inherent limitations, however, and have notfound widespread clinical applications. First, most of the hand heldablation devices (Bicap probe, APC, cryoablation) are point and shootdevices that create small foci of ablation. This ablation mechanism isoperator dependent, cumbersome and time consuming. Second, because thetarget tissue is moving due to patient movement, respiration movement,normal peristalsis and vascular pulsations, the depth of ablation of thetarget tissue is inconsistent and results in a non-uniform ablation.Superficial ablation results in incomplete ablation with residualneoplastic tissue left behind. Deeper ablation results in complicationssuch as bleeding, stricture formation and perforation. All of theselimitations and complications have been reported with conventionaldevices.

For example, radiofrequency ablation uses a rigid bipolar balloon basedelectrode and radiofrequency thermal energy. The thermal energy isdelivered by direct contact of the electrode with the diseased Barrettepithelium allowing for a relatively uniform, large area ablation.However, the rigid electrode does not accommodate for variations inesophageal size and is ineffective in ablating tortuous esophagus,proximal esophageal lesions as an esophagus narrows towards the top, andesophagus at the gastroesophagal junction due to changes in theesophagus diameter. Nodular disease in Barrett esophagus also cannot betreated using the rigid bipolar RF electrode. Due to its size andrigidity, the electrode cannot be passed through the scope. In additionsticking of sloughed tissue to the electrode impedes with delivery ofradiofrequency energy resulting in incomplete ablation. The electrodesize is limited to 3 cm, thus requiring repeat applications to treatlarger lengths of Barrett esophagus.

Photodynamic therapy (PDT) is a two part procedure that involvesinjecting a photo-sensitizer that is absorbed and retained by theneoplastic and pre-neoplastic tissue. The tissue is then exposed to aselected wavelength of light which activates the photo-sensitizer andresults in tissue destruction. PDT is associated with complications suchas stricture formation and photo-sensitivity which has limited its useto the most-advanced stages of the disease. In addition, patchy uptakeof the photosensitizer results in incomplete ablation and residualneoplastic tissue.

Cryoablation of the esophageal tissues via direct contact with a liquidnitrogen has been studied in both animal models and humans (Rodgers etal, Cryobiology, 22:86-92 (1985); Rodgers et al, Ann. Thorac. Surq.55:52-7 [1983]) and has been used to treat Barrett esophagus and(Johnston et al. Gastrointest Endosc) early esophageal cancer (Grana etal, Int. Surg., 66:295 [1981]). A spray catheter that directly spraysliquid N₂ or CO₂ (cryoablation) or argon (APC) to ablate Barrett tissuein the esophagus has been described. These techniques suffer theshortcoming of the traditional hand-held devices. Treatment using thisprobe is cumbersome and requires operator control under directendoscopic visualization. Continuous movement in the esophagus due torespiration or cardiac or aortic pulsations or movement causes an unevendistribution of the ablative agent and results in non-uniform and/orincomplete ablation. Close or direct contact of the catheter to thesurface epithelium may cause deeper tissue injury, resulting inperforation, bleeding or stricture formation. Too distant a placement ofthe catheter due to esophageal movement will result in incompleteBarrett ablation, requiring multiple treatment sessions or buriedlesions with a continued risk of esophageal cancer. Expansion ofcryogenic gas in the esophagus results in uncontrolled retching whichmay result in esophageal tear or perforation requiring continuedsuctioning of cryogen.

Colon polyps are usually resected using snare resection with or withoutthe use of monopolar cautery. Flat polyps or residual polyps after snareresection have been treated with argon plasma coagulation or lasertreatment. Both these treatments, have the previously mentionedlimitations. Hence, most large flat polyps undergo surgical resectiondue to high risk of bleeding, perforation and residual disease usingtraditional endoscopic resection or ablation techniques.

Most of the conventional balloon catheters traditionally used for tissueablation either heat or cool the balloon itself or a heating elementsuch as a radio frequency (RF) coils mounted on the balloon. Thisrequires direct contact of the balloon catheter with the ablatedsurface. When the balloon catheter is deflated, the epithelium sticks tothe catheter and sloughs off, thereby causing bleeding. Blood caninterfere with delivery of energy i.e. energy sink. In additionreapplication of energy will result in deeper burn in the area wheresuperficial lining has sloughed. Further, balloon catheters cannot beemployed for treatment in non cylindrical organs, like the uterus orsinuses, and also do not provide non-circumferential or focal ablationin a hollow organ. Additionally, if used with cryogens as ablativeagents, which expand exponentially upon being heated, balloon cathetersmay result in a closed cavity and trap the escape of cryogen, resultingin complications such as perforations and tears.

Accordingly, there is a need in the art for an improved method andsystem for delivering ablative agents to a tissue surface, for providinga consistent, controlled, and uniform ablation of the target tissue, andfor minimizing the adverse side effects of introducing ablative agentsinto a patient.

SUMMARY OF THE INVENTION

The present invention is directed toward a device to perform ablation ofendometrial tissue, comprising a catheter having a shaft through whichan ablative agent can travel, a first positioning element attached tosaid catheter shaft at a first position, wherein said first positioningelement is configured to center said catheter in a center of a cervix,and a second positioning element attached to said catheter shaft at asecond position, wherein the shaft comprises a plurality of portsthrough which said ablative agent can be released out of said shaft andwherein said ports are located between said first position and secondposition.

Optionally, the first positioning element is conical. The firstpositioning element comprises an insulated membrane which can beconfigured to prevent an escape of thermal energy through the cervix.The second positioning element is disc shaped. The second positioningelement has a dimension which can be used to determine a uterine cavitysize. The second positioning element has a dimension which can be usedto calculate an amount of thermal energy needed to ablate theendometrial tissue. The device also includes at least one temperaturesensor, which can be used to control delivery of the ablative agent,such as steam.

Optionally, the second positioning element is separated from endometrialtissue to be ablated by a distance of greater than 0.1 mm. The firstpositioning element is a covered wire mesh. The first positioningelement is comprises a circular body with a diameter between 0.1 mm and10 cm. The second positioning element is oval and wherein said oval hasa long axis between 0.1 mm and 10 cm and a short axis between 0.1 mm and5 cm.

In another embodiment, the present invention is directed toward a deviceto perform ablation of endometrial tissue, comprising a catheter havinga hollow shaft through which steam can be delivered, a first positioningelement attached to said catheter shaft at a first position, whereinsaid first positioning element is conical and configured to center saidcatheter in a center of a cervix, a second positioning element attachedto said catheter shaft at a second position, wherein the secondpositioning element is disc shaped, a plurality of ports integrallyformed in said catheter shaft, wherein steam can be released out of saidports and directed toward endometrial tissue and wherein said ports arelocated between said first position and second position; and at leastone temperature sensor.

Optionally, the second positioning element has a dimension, which can beused to determine a uterine cavity size. The second positioning elementhas a dimension, which can be used to calculate an amount of thermalenergy needed to ablate the endometrial tissue. The temperature sensorsare used to control delivery of said ablative agent. The firstpositioning element comprises wire mesh. The second positioning elementhas a disc shape that is oval and wherein said oval has a long axisbetween 0.1 mm and 10 cm and a short axis between 0.1 mm and 5 cm.

A device to perform ablation of tissue in a hollow organ, comprising acatheter having a shaft through which an ablative agent can travel; afirst positioning element attached to said catheter shaft at a firstposition, wherein said first positioning element is configured toposition said catheter at a predefined distance from the tissue to beablated; and wherein the shaft comprises one or more port through whichsaid ablative agent can be released out of said shaft.

Optionally, the device further comprises a second positioning elementattached to said catheter shaft at a position different from said firstpositioning element. The first positioning element is at least one of aconical shape, disc shape, or a free form shape conformed to the shapeof the hollow organ. The second positioning element has predefineddimensions and wherein said predefined dimensions are used to determinethe dimensions of the hollow organ to be ablated. The first positioningelement comprises an insulated membrane. The insulated membrane isconfigured to prevent an escape of thermal energy. The secondpositioning element is at least one of a conical shape, disc shape, or afree form shape conformed to the shape of the hollow organ. The secondpositioning element has predefined dimensions and wherein saidpredefined dimensions are used to determine the dimensions of the holloworgan to be ablated. The second positioning element has a predefineddimension and wherein said predefined dimension is used to calculate anamount of thermal energy needed to ablate the tissue. The device furthercomprises at least one temperature sensor. The temperature sensor isused to control delivery of said ablative agent. The ablative agent issteam. The first positioning element is a covered wire mesh. The firstpositioning element comprises a circular body with a diameter between0.01 mm and 10 cm. The first positioning element is oval and whereinsaid oval has a long axis between 0.01 mm and 10 cm and a short axisbetween 0.01 mm and 9 cm.

In another embodiment, the present invention is directed to a device toperform ablation of tissue in a hollow organ, comprising a catheterhaving a hollow shaft through which steam can be delivered; a firstpositioning element attached to said catheter shaft at a first position,wherein said first positioning element is configured to position saidcatheter at a predefined distance from the surface of the hollow organ;a second positioning element attached to said catheter shaft at a secondposition, wherein the second positioning element is shaped to positionsaid catheter at a predefined distance from the surface of the holloworgan; a plurality of ports integrally formed in said catheter shaft,wherein steam can be released out of said ports and directed towardtissue to be ablated and wherein said ports are located between saidfirst position and second position; and at least one temperature sensor.

Optionally, the first positioning element has a predefined dimension andwherein said dimension is used to determine the size of the holloworgan. The second positioning element has a predefined dimension andwherein said dimension is used to calculate an amount of thermal energyneeded to ablate the tissue. The temperature sensor is used to controldelivery of said ablative agent. The first positioning element compriseswire mesh. The second positioning element has a disc shape that is ovaland wherein said oval has a long axis between 0.01 mm and 10 cm and ashort axis between 0.01 mm and 9 cm.

In another embodiment, the present invention is directed to a device toperform ablation of the gastrointestinal tissue, comprising a catheterhaving a shaft through which an ablative agent can travel; a firstpositioning element attached to said catheter shaft at a first position,wherein said first positioning element is configured to position thecatheter at a fixed distance from the gastrointestinal tissue to beablated, and wherein said first positioning element is separated from anablation region by a distance of between 0 mm and 5 cm, and an inputport at a second position and in fluid communication with said cathetershaft in order to receive said ablative agent wherein the shaftcomprises one or more ports through which said ablative agent can bereleased out of said shaft.

Optionally, the first positioning element is at least one of aninflatable balloon, wire mesh disc or cone. By introducing said ablativeagent into said ablation region, the device creates an gastrointestinalpressure equal to or less than 5 atm. The ablative agent has atemperature between −100 degrees Celsius and 200 degrees Celsius. Thecatheter further comprises a temperature sensor. The catheter furthercomprises a pressure sensor. The first positioning element is configuredto abut a gastroesophageal junction when placed in a gastric cardia. Theports are located between said first position and second position. Thediameter of the positioning element is between 0.01 mm and 100 mm. Theablative agent is steam. The first positioning element comprises acircular body with a diameter between 0.01 mm and 10 cm.

In another embodiment, the present invention is directed toward a deviceto perform ablation of esophageal tissue, comprising a catheter having ahollow shaft through which steam can be transported; a first positioningelement attached to said catheter shaft at a first position, whereinsaid first positioning element is configured to abut a gastroesophagealjunction when placed in a gastric cardia; and an input port at a secondposition and in fluid communication with said catheter shaft in order toreceive said steam wherein the shaft comprises a plurality of portsthrough which said steam can be released out of said shaft and whereinsaid ports are located between said first position and second position.The device further comprises a temperature sensor wherein saidtemperature sensor is used to control the release of said steam. Thefirst positioning element comprises at least one of a wire mesh disc, awire mesh cone, or an inflatable balloon. The first positioning elementis separated from an ablation region by a distance of between 0 mm and 1cm. The diameter of the first positioning element is between 1 mm and100 mm.

In another embodiment, the present invention is directed to a device toperform ablation of gastrointestinal tissue, comprising a catheterhaving a hollow shaft through which steam can be transported; a firstpositioning element attached to said catheter shaft at a first position,wherein said first positioning element is configured to abut thegastrointestinal tissue; and an input port at a second position and influid communication with said catheter shaft in order to receive saidsteam wherein the shaft comprises one or more ports through which saidsteam can be released out of said shaft onto the gastrointestinaltissue.

Optionally, the device further comprises a temperature sensor whereinsaid temperature sensor is used to control the release of said steam.The first positioning element comprises at least one of a wire mesh discand a wire mesh cone. The diameter of the first positioning element is0.1 mm to 50 mm. The device is used to perform non-circumferentialablation.

In another embodiment, the present invention is directed to a device toperform ablation of endometrial tissue, comprising a catheter having ashaft through which an ablative agent can travel; a first positioningelement attached to said catheter shaft at a first position, whereinsaid first positioning element is configured to center said catheter ina center of a cervix; and a shaft comprises a plurality of ports throughwhich said ablative agent can be released out of said shaft.

Optionally, the device further comprises a second positioning elementattached to said catheter shaft at a second position. The firstpositioning element is conical. The first positioning element comprisesan insulated membrane. The insulated membrane is configured to preventan escape of thermal energy through the cervix. The second positioningelement is disc shaped. The second positioning element has a predefineddimension and wherein said dimension is used to determine a uterinecavity size. The second positioning element has a predefined dimensionand wherein said dimension is used to calculate an amount of thermalenergy needed to ablate the endometrial tissue. The device furthercomprises at least one temperature sensor wherein said temperaturesensor is used to control delivery of said ablative agent. The ablativeagent is steam. The first positioning element is a covered wire mesh.The first positioning element comprises a circular body with a diameterbetween 0.01 mm and 10 cm. The second positioning element is oval andwherein said oval has a long axis between 0.01 mm and 10 cm and a shortaxis between 0.01 mm and 5 cm.

In another embodiment, the present invention is directed toward a deviceto perform ablation of endometrial tissue, comprising a catheter havinga hollow shaft through which steam can be delivered; a first positioningelement attached to said catheter shaft at a first position, whereinsaid first positioning element is conical and configured to center saidcatheter in a center of a cervix; a second positioning element attachedto said catheter shaft at a second position, wherein the secondpositioning element is elliptical shaped; a plurality of portsintegrally formed in said catheter shaft, wherein steam can be releasedout of said ports and directed toward endometrial tissue and whereinsaid ports are located between said first position and second position;and at least one temperature sensor.

Optionally, the second positioning element has a predefined dimensionand wherein said dimension is used to determine a uterine cavity size.The second positioning element has a diameter and wherein said diameteris used to calculate an amount of thermal energy needed to ablate theendometrial tissue. The temperature sensors are used to control deliveryof said ablative agent. The first positioning element comprises wiremesh. The second positioning element has a disc shape that is oval andwherein said oval has a long axis between 0.01 mm and 10 cm and a shortaxis between 0.01 mm and 5 cm.

Optionally, the second positioning element can use one or more sourcesof infrared, electromagnetic, acoustic or radiofrequency energy tomeasure the dimensions of the hollow cavity. The energy is emitted fromthe sensor and is reflected back to the detector in the sensor. Thereflected data is used to determine the dimension of the hollow cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described by way of embodiments illustrated inthe accompanying drawings wherein:

FIG. 1. illustrates an ablation device, in accordance with an embodimentof the present invention;

FIG. 2 a illustrates a longitudinal section of an ablation device withports distributed thereon;

FIG. 2 b illustrates a cross section of a port on the ablation device,in accordance with an embodiment of the present invention;

FIG. 2 c illustrates a cross section of a port on the ablation device,in accordance with another embodiment of the present invention;

FIG. 2 d illustrates a catheter of the ablation device, in accordancewith an embodiment of the present invention;

FIG. 3 a. illustrates the ablation device placed in an uppergastrointestinal tract with Barrett esophagus to selectively ablate theBarrett tissue, in accordance with an embodiment of the presentinvention;

FIG. 3 b. illustrates the ablation device placed in an uppergastrointestinal tract with Barrett esophagus to selectively ablate theBarrett tissue, in accordance with another embodiment of the presentinvention;

FIG. 3 c is a flowchart illustrating the basic procedural steps forusing the ablation device, in accordance with an embodiment of thepresent invention;

FIG. 4 a illustrates the ablation device placed in a colon to ablate aflat colon polyp, in accordance with an embodiment of the presentinvention;

FIG. 4 b illustrates the ablation device placed in a colon to ablate aflat colon polyp, in accordance with another embodiment of the presentinvention;

FIG. 5 a illustrates the ablation device with a coaxial catheter design,in accordance with an embodiment of the present invention;

FIG. 5 b illustrates a partially deployed positioning device, inaccordance with an embodiment of the present invention;

FIG. 5 c illustrates a completely deployed positioning device, inaccordance with an embodiment of the present invention;

FIG. 5 d illustrates the ablation device with a conical positioningelement, in accordance with an embodiment of the present invention;

FIG. 5 e illustrates the ablation device with a disc shaped positioningelement, in accordance with an embodiment of the present invention;

FIG. 6 illustrates an upper gastrointestinal tract with a bleedingvascular lesion being treated by the ablation device, in accordance withan embodiment of the present invention;

FIG. 7 illustrates endometrial ablation being performed in a femaleuterus by using the ablation device, in accordance with an embodiment ofthe present invention;

FIG. 8 illustrates sinus ablation being performed in a nasal passage byusing the ablation device, in accordance with an embodiment of thepresent invention;

FIG. 9 illustrates bronchial and bullous ablation being performed in apulmonary system by using the ablation device, in accordance with anembodiment of the present invention;

FIG. 10 illustrates prostate ablation being performed on an enlargedprostrate in a male urinary system by using the device, in accordancewith an embodiment of the present invention;

FIG. 11 illustrates fibroid ablation being performed in a female uterusby using the ablation device, in accordance with an embodiment of thepresent invention;

FIG. 12 illustrates a vapor delivery system using an RF heater forsupplying vapor to the ablation device, in accordance with an embodimentof the present invention; and

FIG. 13 illustrates a vapor delivery system using a resistive heater forsupplying vapor to the ablation device, in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an ablation device comprising a catheterwith one or more centering or positioning attachments at one or moreends of the catheter to affix the catheter and its infusion port at afixed distance from the ablative tissue which is not affected by themovements of the organ. The arrangement of one or more spray portsallows for uniform spray of the ablative agent producing a uniformablation of large area such as Barrett esophagus. The flow of ablativeagent is controlled by the microprocessor and depends upon one or moreof the length or area of tissue to be ablated, type and depth of tissueto be ablated and distance of the infusion port from the tissue to beablated.

“Treat,” “treatment,” and variations thereof refer to any reduction inthe extent, frequency, or severity of one or more symptoms or signsassociated with a condition.

“Duration” and variations thereof refer to the time course of aprescribed treatment, from initiation to conclusion, whether thetreatment is concluded because the condition is resolved or thetreatment is suspended for any reason. Over the duration of treatment, aplurality of treatment periods may be prescribed during which one ormore prescribed stimuli are administered to the subject.

“Period” refers to the time over which a “dose” of stimulation isadministered to a subject as part of the prescribe treatment plan.

The term “and/or” means one or all of the listed elements or acombination of any two or more of the listed elements.

The terms “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims.

Unless otherwise specified, “a,” “an,” “the,” “one or more,” and “atleast one” are used interchangeably and mean one or more than one.

For any method disclosed herein that includes discrete steps, the stepsmay be conducted in any feasible order. And, as appropriate, anycombination of two or more steps may be conducted simultaneously.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.). Unless otherwise indicated, all numbersexpressing quantities of components, molecular weights, and so forthused in the specification and claims are to be understood as beingmodified in all instances by the term “about.” Accordingly, unlessotherwise indicated to the contrary, the numerical parameters set forthin the specification and claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. All numerical values, however, inherently contain a rangenecessarily resulting from the standard deviation found in theirrespective testing measurements.

Ablative agents such as steam, heated gas or cryogens such as but notlimited to liquid nitrogen are inexpensive and readily available, andare directed via the infusion port onto the tissue, held at a fixed andconsistent distance, targeted for ablation. This allows for uniformdistribution of the ablative agent on the targeted tissue. The flow ofthe ablative agent is controlled by a microprocessor according to apredetermined method based on the characteristic of the tissue to beablated, required depth of ablation, and distance of the port from thetissue. The microprocessor may use temperature, pressure or othersensing data to control the flow of the ablative agent. In addition, oneor more suction ports are provided to suction the ablation agent fromthe vicinity of the targeted tissue. The targeted segment can be treatedby a continuous infusion of the ablative agent or via cycles of infusionand removal of the ablative agent as determined and controlled by themicroprocessor.

It should be appreciated that the devices and embodiments describedherein are implemented in concert with a controller that comprises amicroprocessor executing control instructions. The controller can be inthe form of any computing device, including desktop, laptop, and mobiledevice, and can communicate control signals to the ablation devices inwired or wireless form.

The following disclosure is provided in order to enable a person havingordinary skill in the art to practice the invention. Exemplaryembodiments are provided only for illustrative purposes and variousmodifications will be readily apparent to persons skilled in the art.The general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the invention. Also, the terminology and phraseology used is for thepurpose of describing exemplary embodiments and should not be consideredlimiting. Thus, the present invention is to be accorded the widest scopeencompassing numerous alternatives, modifications and equivalentsconsistent with the principles and features disclosed. For purpose ofclarity, details relating to technical material that is known in thetechnical fields related to the invention have not been described indetail so as not to unnecessarily obscure the present invention. Thepresent invention will now be discussed in context of embodiments asillustrated by the accompanying drawings.

FIG. 1 illustrates an ablation device, in accordance with an embodimentof the present invention. The ablation device comprises a catheter 10having a distal centering or positioning attachment which is aninflatable balloon 11. The catheter 10 is made of or covered with aninsulated material to prevent the escape of ablative energy from thecatheter body. The ablation device comprises one or more infusion ports12 for the infusion of ablative agent and one or more suction ports 13for the removal of ablative agent. In one embodiment, the infusion port12 and suction port 13 are the same. Ablative agent is stored in areservoir 14 connected to the catheter 10. Delivery of the ablativeagent is controlled by a microprocessor 15 and initiation of thetreatment is controlled by a treating physician using an input device,such as a foot-paddle 16. In other embodiments, the input device couldbe a voice recognition system (that is responsive to commands such as“start”, “more”, “less”, etc.), a mouse, a switch, footpad, or any otherinput device known to persons of ordinary skill in the art. In oneembodiment, microprocessor 15 translates signals from the input device,such as pressure being placed on the foot-paddle or vocal commands toprovide “more” or “less” ablative agent, into control signals thatdetermine whether more or less ablative agent is dispensed. Optionalsensor 17 monitors changes in an ablative tissue or its vicinity toguide flow of ablative agent. Optional infrared, electromagnetic,acoustic or radiofrequency energy emitter and sensor 18 measures thedimensions of the hollow organ.

In one embodiment, the inflatable balloon has a diameter of between 1 mmand 10 cm. In one embodiment, the inflatable balloon is separated fromthe ports by a distance of 1 mm to 10 cm. In one embodiment, the size ofthe port openings are between 1 μm and 1 cm. It should be appreciatedthat the inflatable balloon is used to fix the device and therefore isconfigured to not contact the ablated area. The inflatable balloon canbe any shape that contacts the hollow organ at 3 or more points. One ofordinary skill in the art that, using triangulation, one can calculatethe distance of the catheter from the lesion. Alternatively theinfrared, electromagnetic, acoustic or radiofrequency energy emitter andsensor 18 can measure the dimensions of the hollow organ. The infrared,electromagnetic, acoustic or radiofrequency energy is emitted from theemitter 18 and is reflected back from the tissue to the detector in theemitter 18. The reflected data can be used to determine the dimension ofthe hollow cavity. It should be appreciated that the emitter and sensor18 can be incorporated into a single transceiver that is capable of bothemitting energy and detecting the reflected energy.

FIG. 2 a illustrates a longitudinal section of the ablation device,depicting a distribution of infusion ports. FIG. 2 b illustrates a crosssection of a distribution of infusion ports on the ablation device, inaccordance with an embodiment of the present invention. The longitudinaland cross sectional view of the catheter 10 as illustrated in FIGS. 2 aand 2 b respectively, show one arrangement of the infusion ports 12 toproduce a uniform distribution of ablative agent 21 in order to providea circumferential area of ablation in a hollow organ 20. FIG. 2 cillustrates a cross section of a distribution of infusion ports on theablation device, in accordance with another embodiment of the presentinvention. The arrangement of the infusion ports 12 as illustrated inFIG. 2 c produce a focal distribution of ablative agent 21 and a focalarea of ablation in a hollow organ 20.

For all embodiments described herein, it should be appreciated that thesize of the port, number of ports, and distance between the ports willbe determined by the volume of ablative agent needed, pressure that thehollow organ can withstand, size of the hollow organ as measured by thedistance of the surface from the port, length of the tissue to beablated (which is roughly the surface area to be ablated),characteristics of the tissue to be ablated and depth of ablationneeded. In one embodiment, there is at least one port opening that has adiameter between 1 μm and 1 cm. In another embodiment, there is two ormore port openings that have a diameter between 1 μm and 1 cm and thatare equally spaced around the perimeter of the device.

FIG. 2 d illustrates another embodiment of the ablation device. Thevapor ablation catheter comprises an insulated catheter 21 with one ormore positioning attachments 22 of known length 23. The vapor ablationcatheter has one or more vapor infusion ports 25. The length 24 of thevapor ablation catheter 21 with infusion ports 25 is determined by thelength or area of the tissue to be ablated. Vapor 29 is deliveredthrough the vapor infusion ports 25. The catheter 21 is preferablypositioned in the center of the positioning attachment 22, and theinfusion ports 25 are arranged circumferentially for circumferentialablation and delivery of vapor. In another embodiment, the catheter 21can be positioned toward the periphery of the positioning attachment 22and the infusion ports 25 can be arranged non-circumferentially,preferably linearly on one side for focal ablation and delivery ofvapor. The positioning attachment 23 is one of an inflatable balloon, awire mesh disc with or without an insulated membrane covering the disc,a cone shaped attachment, a ring shaped attachment or a freeformattachment designed to fit the desired hollow body organ or hollow bodypassage, as further described below. Optional infrared, electromagnetic,acoustic or radiofrequency energy emitter and sensor 28 are incorporatedto measures the dimensions of the hollow organ.

The vapor ablation catheter may also comprise an optional coaxial sheet27 to restrain the positioning attachment 22 in a manner comparable to acoronary metal stent. In one embodiment, the disc is made of memorymetal or memory material with a compressed linear form and anon-compressed form in the shape of the positioning attachment.Alternatively, the channel of an endoscope may perform the function ofrestraining the positioning attachment 22 by, for example, acting as aconstraining sheath. Optional sensor 26 is deployed on the catheter tomeasure changes associated with vapor delivery or ablation. The sensoris one of temperature, pressure, photo or chemical sensor.

Optional, one or more, infrared, electromagnetic, acoustic orradiofrequency energy emitter and sensor 28 can measure the dimensionsof the hollow organ. The infrared, electromagnetic, acoustic orradiofrequency energy is emitted from the emitter 18 and is reflectedback from the tissue to the detector in the emitter 18. The reflecteddata can be used to determine the dimension of the hollow cavity. Themeasurement is performed at one or multiple points to get an accurateestimate of the dimension of the hollow organ. The data can also be usedto create a topographic representation of the hollow organ.

FIG. 3 a illustrates the ablation device placed in an uppergastrointestinal tract with Barrett esophagus to selectively ablate theBarrett tissue, in accordance with an embodiment of the presentinvention. The upper gastrointestinal tract comprises Barrett esophagus31, gastric cardia 32, gastroesophageal junction 33 and displacedsquamo-columnar junction 34. The area between gastroesophageal junction33 and displaced squamo-columnar junction 34 is Barrett esophagus 31,which is targeted for ablation. Distal to the cardia 32 is the stomach35 and proximal to the cardia 32 is the esophagus 36. The ablationdevice is passed into the esophagus 36 and the positioning device 11 isplaced in the gastric cardia 32 abutting the gastroesophageal junction33. This affixes the ablation catheter 10 and its ports 12 in the centerof the esophagus 36 and allows for uniform delivery of the ablativeagent 21 to the Barrett esophagus 31. In one embodiment, the positioningdevice is first affixed to an anatomical structure, not being subjectedto ablation, before ablation occurs. Where the patient is undergoingcircumferential ablation or first time ablation, the positioningattachment is preferably placed in the gastric cardia, abutting thegastroesophageal junction. Where the patient is undergoing a focalablation of any residual disease, it is preferable to use the cathetersystem shown in FIG. 4 b, as discussed below. In one embodiment, thepositioning attachment must be separated from the ablation region by adistance of greater than 0 mm, preferably 1 mm and ideally 1 cm. In oneembodiment, the size of the positioning device is in the range of 10 to100 mm, preferably 20-40 mm, although one of ordinary skill in the artwould appreciate that the precise dimensions are dependent on the sizeof the patient's esophagus.

The delivery of ablative agent 21 through the infusion port 12 iscontrolled by the microprocessor 15 coupled with the ablation device.The delivery of ablative agent is guided by predetermined programmaticinstructions, depending on the tissue to be ablated and the depth ofablation required. In one embodiment, the target procedural temperaturewill need to be between −100 degrees Celsius and 200 degrees Celsius,preferably between 50 degrees Celsius and 75 degrees Celsius, as furthershown in the dosimetery table below. In one embodiment, esophagealpressure should not to exceed 5 atm, and is preferably below 0.5 atm. Inone embodiment, the target procedural temperature is achieved in lessthan 1 minute, preferably in less than 5 seconds, and is capable ofbeing maintained for up to 10 minutes, preferably 1 to 10 seconds, andthen cooled to body temperature. One of ordinary skill in the art wouldappreciate that the treatment can be repeated until the desired ablationeffect is achieved.

Optional sensor 17 monitors intraluminal parameters such as temperatureand pressure and can increase or decrease the flow of ablative agent 21through the infusion port 12 to obtain adequate heating or cooling,resulting in adequate ablation. The sensor 17 monitors intraluminalparameters such as temperature and pressure and can increase or decreasethe removal of ablative agent 21 through the optional suction port 13 toobtain adequate heating or cooling resulting in adequate ablation ofBarrett esophagus 31. FIG. 3 b illustrates the ablation device placed inan upper gastrointestinal tract with Barrett esophagus to selectivelyablate the Barrett tissue, in accordance with another embodiment of thepresent invention. As illustrated in FIG. 3 b, the positioning device 11is a wire mesh disc. In one embodiment, the positioning attachment mustbe separated from the ablation region by a distance of greater than 0mm, preferably 1 mm and ideally 1 cm. In one embodiment, the positioningattachment is removably affixed to the cardia or EG junction (for thedistal attachment) or in the esophagus by a distance of greater than 0.1mm, preferably around 1 cm, above the proximal most extent of theBarrett tissue (for the proximal attachment).

FIG. 3 b is another embodiment of the Barrett ablation device where thepositioning element 11 is a wire mesh disc. The wire mesh may haveoptional insulated membrane to prevent the escape of the ablative agent.In the current embodiment, two wire mesh discs are used to center theablation catheter in the esophagus. The distance between the two discsis determined by the length of the tissue to ablated which, in thiscase, would be the length of the Barrett esophagus. Optional infrared,electromagnetic, acoustic or radiofrequency energy emitter and sensor 18are incorporated to measures the diameter of the esophagus.

FIG. 3 c is a flowchart illustrating the basic procedural steps forusing the ablation device, in accordance with an embodiment of thepresent invention. At step 302, a catheter of the ablation device isinserted into a hollow organ which is to be ablated. For example, inorder to perform ablation in a Barrett esophagus of a patient thecatheter is inserted into the Barrett esophagus via the esophagus of thepatient.

At step 304, a positioning element of the ablation device is deployed.In an embodiment, where the positioning element is a balloon, theballoon is inflated in order to position the ablation device at a knownfixed distance from the tissue to be ablated. The diameter of the holloworgan may either be predetermined by using radiological tests such asbarium X-rays or computer tomography (CT) scan, or by using pressurevolume cycle, i.e by determining volume needed to raise pressure to afixed level (say 1 atm) in a fixed volume balloon. In anotherembodiment, where the positioning device is disc shaped, circumferentialrings are provided in order to visually communicate to an operatingphysician the diameter of the hollow organ. In various embodiments ofthe present invention, the positioning device enables centering of thecatheter of the ablation device in a non-cylindrical body cavity, andthe volume of the cavity is measured by the length of catheter or auterine sound.

Optional, one or more, infrared, electromagnetic, acoustic orradiofrequency energy emitter and sensor can be used to measure thedimensions of the hollow organ. The infrared, electromagnetic, acousticor radiofrequency energy is emitted from the emitter and is reflectedback from the tissue to a detector in the emitter. The reflected datacan be used to determine the dimension of the hollow cavity. Themeasurement can be performed at one or multiple points to get anaccurate estimate of the dimension of the hollow organ. The data frommultiple points can also be used to create a topographic representationof the hollow organ or to calculate the volume of the hollow organ.

In one embodiment, the positioning attachment must be separated from theports by a distance of 0 mm or greater, preferably greater than 0.1 mm,and more preferably 1 cm. The size of the positioning device depends onthe hollow organ being ablated and ranges from 1 mm to 10 cm. In oneembodiment, the diameter of the positioning element is between 0.01 mmand 100 mm. In one embodiment, the first positioning element comprises acircular body with a diameter between 0.01 mm and 10 cm.

At step 306, the organ is ablated by automated delivery of an ablativeagent such as steam via infusion ports provided on the catheter. Thedelivery of the ablative agent through the infusion ports is controlledby a microprocessor coupled with the ablation device. The delivery ofablative agent is guided by predetermined programmatic instructionsdepending on the tissue to be ablated and the depth of ablationrequired. In an embodiment of the present invention where the ablativeagent is steam, the dose of the ablative agent is determined byconducting dosimetery study to determine the dose to ablate endometrialtissue. The variable that enables determination of total dose ofablative agent is the volume (or mass) of the tissue to be treated whichis calculated by using the length of the catheter and diameter of theorgan (for cylindrical organs). The determined dose of ablative agent isthen delivered using micro-processor controlled steam generator.

In one embodiment, the dose is provided by first determining what thedisorder being treated is and what the desired tissue effect is, andthen finding the corresponding temperature, as shown in the tablesbelow.

Temp Tissue Effect 37-40 No significant tissue effect 41-44 Reversiblecell damage in few hours 45-49 Irreversible cell damage at shorterintervals 50-69 Irreversible cell damage-ablation necrosis at shorterintervals 70 Threshold temp for tissue shrinkage, H-bond breakage 70-99Coagulation and Hemostasis 100-200 Desiccation and Carbonization oftissue >200 Charring of tissue glucose

Disorder Max. Temp ENT/Pulmonary Nasal Polyp 60-80 C. Turbinectomy 70-85C. Bullous Disease 70-85 C. Lung Reduction 70-85 C. GenitourinaryUterine Menorrhagia 80-90 C. Endometriosis 80-90 C. Uterine Fibroids90-100 C. Benign Prostatic Hypertrophy 90-100 C. GastroenterologyBarrett Esophagus 60-75 C. Esophageal Dysplasia 60-80 C. Vascular GIDisorders 55-75 C. Flat Polyps 60-80 C.

In addition, the depth of ablation desired determines the holding timeat the maximum temperature. For superficial ablation (Barrett), theholding time at the maximum temperature is very short (flash burn) anddoes not allow for heat to transfer to the deeper layers. This willprevent damage to deeper normal tissue and hence prevention patientdiscomfort and complication. For deeper tissue ablation, the holdingtime at the maximum temperature will be longer, thereby allowing theheat to percolate deeper.

FIG. 4 a illustrates the ablation device placed in a colon to ablate aflat colon polyp, in accordance with an embodiment of the presentinvention. The ablation catheter 10 is passed through a colonoscope 40.The positioning device 11 is placed proximal to a flat colonic polyp 41which is to be ablated, in the normal colon 42. The positioning device11 is one of an inflatable balloon, a wire mesh disc with or without aninsulated membrane covering the disc, a cone shaped attachment, a ringshaped attachment or a freeform attachment designed to fit the coloniclumen. The positioning device 11 has the catheter 10 located toward theperiphery of the positioning device 11 placing it closer to the polyp 41targeted for non-circumferential ablation. Hence, the positioning device11 fixes the catheter to the colon 42 at a predetermined distance fromthe polyp 41 for uniform and focused delivery of the ablative agent 21.The delivery of ablative agent 21 through the infusion port 12 iscontrolled by the microprocessor 15 attached to the ablation device anddepends on tissue and the depth of ablation required. The delivery ofablative agent 21 is guided by predetermined programmatic instructionsdepending on the tissue to be ablated and the area and depth of ablationrequired. The ablation device allows for focal ablation of diseasedpolyp mucosa without damaging the normal colonic mucosa located awayfrom the catheter ports.

In one embodiment, the positioning attachment must be separated from theablation region by a distance of greater than 0.1 mm, ideally more than5 mm. In one embodiment, the positioning element is proximal to thecolon polyp. For this application, the embodiment shown in FIG. 4 bwould be preferred.

FIG. 4 b illustrates the ablation device placed in a colon to ablate aflat colon polyp, in accordance with another embodiment of the presentinvention. As illustrated in FIG. 4 b, the positioning device is aconical attachment at the tip of the catheter. The conical attachmenthas a known length ‘l’ and diameter ‘d’ that is used to calculate theamount of thermal energy needed to ablate the flat colon polyp. In oneembodiment, the positioning attachment must be separated from theablation region by a distance of greater than 0.1 mm, preferably 1 mmand more preferably 1 cm. In one embodiment, the length ‘l’ is greaterthan 0.1 mm, preferably between 5 and 10 mm. In one embodiment, diameter‘d’ depends on the size of the polyp and can be between 1 mm and 10 cm,preferably 1 to 5 cm. This embodiment can also be used to ablateresidual neoplastic tissue at the edges after endoscopic snare resectionof a large sessile colon polyp.

FIG. 5 a illustrates the ablation device with a coaxial catheter design,in accordance with an embodiment of the present invention. The coaxialdesign has a handle 52 a, an infusion port 53 a, an inner sheath 54 aand an outer sheath 55 a. The outer sheath 55 a is used to constrain thepositioning device 56 a in the closed position and encompasses ports 57a. FIG. 5 b shows a partially deployed positioning device 56 b, with theports 57 b still within the outer sheath 55 b. The positioning device 56b is partially deployed by pushing the catheter 54 b out of sheath 55 b.

FIG. 5 c shows a completely deployed positioning device 56 c. Theinfusion ports 57 c are out of the sheath 55 c. The length ‘l’ of thecatheter 54 c that contains the infusion port 57 c and the diameter ‘d’of the positioning element 56 c are predetermined/known and are used tocalculate the amount of thermal energy needed. FIG. 5 d illustrates aconical design of the positioning element. The positioning element 56 dis conical with a known length ‘l’ and diameter ‘d’ that is used tocalculate the amount of thermal energy needed for ablation. FIG. 5 eillustrates a disc shaped design of the positioning element 56 ecomprising circumferential rings 59 e. The circumferential rings 59 eare provided at a fixed predetermined distance and are used to estimatethe diameter of a hollow organ or hollow passage in a patient's body.

FIG. 6 illustrates an upper gastrointestinal tract with a bleedingvascular lesion being treated by the ablation device, in accordance withan embodiment of the present invention. The vascular lesion is a visiblevessel 61 in the base of an ulcer 62. The ablation catheter 63 is passedthough the channel of an endoscope 64. The conical positioning element65 is placed over the visible vessel 61. The conical positioning element65 has a known length ‘l’ and diameter ‘d’, which are used to calculatethe amount of thermal energy needed for coagulation of the visiblevessel to achieve hemostasis. The conical positioning element has anoptional insulated membrane that prevents escape of thermal energy orvapor away from the disease site.

In one embodiment, the positioning attachment must be separated from theablation region by a distance of greater than 0.1 mm, preferably 1 mmand more preferably 1 cm. In one embodiment, the length ‘l’ is greaterthan 0.1 mm, preferably between 5 and 10 mm. In one embodiment, diameter‘d’ depends on the size of the lesion and can be between 1 mm and 10 cm,preferably 1 to 5 cm.

FIG. 7 illustrates endometrial ablation being performed in a femaleuterus by using the ablation device, in accordance with an embodiment ofthe present invention. A cross-section of the female genital tractcomprising a vagina 70, a cervix 71, a uterus 72, an endometrium 73,fallopian tubes 74, ovaries 75 and the fundus of the uterus 76 isillustrated. A catheter 77 of the ablation device is inserted into theuterus 72 through the cervix 71. In an embodiment, the catheter 77 hastwo positioning elements, a conical positioning element 78 and a discshaped positioning element 79. The positioning element 78 is conicalwith an insulated membrane covering the conical positioning element 78.The conical element 78 positions the catheter 77 in the center of thecervix 71 and the insulated membrane prevents the escape of thermalenergy or ablative agent through the cervix 71. The second disc shapedpositioning element 79 is deployed close to the fundus of the uterus 76positioning the catheter 71 in the middle of the cavity. An ablativeagent 778 is passed through infusion ports 777 for uniform delivery ofthe ablative agent 778 into the uterine cavity. Predetermined length “l”of the ablative segment of the catheter and diameter ‘d’ of thepositioning element 79 allows for estimation of the cavity size and isused to calculate the amount of thermal energy needed to ablate theendometrial lining. Optional temperature sensors 7 deployed close to theendometrial surface are used to control the delivery of the ablativeagent 778. Optional topographic mapping using multiple infrared,electromagnetic, acoustic or radiofrequency energy emitter and sensorcan be used to define cavity size and shape in patients with irregularor deformed uterine cavity due to conditions such as fibroids.

In an embodiment, the ablative agent is steam which contracts oncooling. Steam turns to water which has a lower volume as compared to acryogen that will expand or a hot fluid used in hydrothermal ablationwhose volume stays constant. With both cryogens and hot fluids,increasing energy delivery is associated with increasing volume of theablative agent which, in turn, requires mechanisms for removing theagent, otherwise the medical provider will run into complications.However, steam, on cooling, turn into water which occupies significantlyless volume; therefore, increasing energy delivery is not associatedwith an increase in volume of the residual ablative agent, therebyeliminating the need for continued removal. This further decreases therisk of leakage of the thermal energy via the fallopian tubes 74 or thecervix 71, thus reducing any risk of thermal injury to adjacent healthytissue.

In one embodiment, the positioning attachment must be separated from theablation region by a distance of greater than 0.1 mm, preferably 1 mmand more preferably 1 cm. In another embodiment, the positioningattachment can be in the ablated region as long as it does not cover asignificant surface area. For endometrial ablation, 100% of the tissuedoes not need to be ablated to achieve the desired therapeutic effect.

In one embodiment, the preferred distal positioning attachment is anuncovered wire mesh that is positioned proximate to the mid body region.In one embodiment, the preferred proximal positioning device is acovered wire mesh that is pulled into the cervix, centers the device,and occludes the cervix. One or more such positioning devices may behelpful to compensate for the anatomical variations in the uterus. Theproximal positioning device is preferably oval, with a long axis beingbetween 0.1 mm and 10 cm (preferably 1 cm to 5 cm) and a short axisbetween 0.1 mm and 5 cm (preferably 0.5 cm to 1 cm). The distalpositioning device is preferably circular with a diameter between 0.1 mmand 10 cm, preferably 1 cm to 5 cm.

FIG. 8 illustrates sinus ablation being performed in a nasal passage byusing the ablation device, in accordance with an embodiment of thepresent invention. A cross-section of the nasal passage and sinusescomprising nares 81, nasal paasages 82, frontal sinus 83, ethemoid sinus84, and diseased sinus epithelim 85 is illustrated. The catheter 86 isinserted into the frontal sinus 83 or the ethemoid sinus 84 through thenares 81 and nasal passages 82.

In an embodiment, the catheter 86 has two positioning elements, aconical positioning element 87 and a disc shaped positioning element 88.The positioning element 87 is conical and has an insulated membranecovering. The conical element 87 positions the catheter 86 in the centerof the sinus opening 80 and the insulated membrane prevents the escapeof thermal energy or ablative agent through the opening. The second discshaped positioning element 88 is deployed in the frontal sinus cavity 83or ethemoid sinus cavity 84, positioning the catheter 86 in the middleof either sinus cavity. The ablative agent 8 is passed through theinfusion port 89 for uniform delivery of the ablative agent 8 into thesinus cavity. The predetermined length “l” of the ablative segment ofthe catheter and diameter ‘d’ of the positioning element 88 allows forestimation of the sinus cavity size and is used to calculate the amountof thermal energy needed to ablate the diseased sinus epithelium 85.Optional temperature sensors 888 are deployed close to the diseasedsinus epithelium 85 to control the delivery of the ablative agent 8. Inan embodiment, the ablative agent 8 is steam which contracts on cooling.This further decreases the risk of leakage of the thermal energy thusreducing any risk of thermal injury to adjacent healthy tissue. In oneembodiment, the dimensional ranges of the positioning elements aresimilar to those in the endometrial application, with preferred maximumranges being half thereof. Optional topographic mapping using multipleinfrared, electromagnetic, acoustic or radiofrequency energy emitter andsensor can be used to define cavity size and shape in patients withirregular or deformed nasal cavity due to conditions such as nasalpolyps.

FIG. 9 illustrates bronchial and bullous ablation being performed in apulmonary system by using the ablation device, in accordance with anembodiment of the present invention. A cross-section of the pulmonarysystem comprising bronchus 91, normal alveolus 92, bullous lesion 93,and a bronchial neoplasm 94 is illustrated.

In one embodiment, the catheter 96 is inserted through the channel of abronchoscope 95 into the bronchus 91 and advanced into a bullous lesion93. The catheter 96 has two positioning elements, a conical positioningelement 97 and a disc shaped positioning element 98. The positioningelement 97 is conical having an insulated membrane covering. The conicalelement 97 positions the catheter 96 in the center of the bronchus 91and the insulated membrane prevents the escape of thermal energy orablative agent through the opening into the normal bronchus. The seconddisc shaped positioning element 98 is deployed in the bullous cavity 93positioning the catheter 96 in the middle of the bullous cavity 93. Anablative agent 9 is passed through the infusion port 99 for uniformdelivery into the sinus cavity. Predetermined length “l” of the ablativesegment of the catheter 96 and diameter ‘d’ of the positioning element98 allow for estimation of the bullous cavity size and is used tocalculate the amount of thermal energy needed to ablate the diseasedbullous cavity 93. Optionally the size of the cavity can be calculatedfrom radiological evaluation using a chest CAT scan or MRI. Optionaltemperature sensors are deployed close to the surface of the bullouscavity 93 to control the delivery of the ablative agent 9. In anembodiment, the ablative agent is steam which contracts on cooling. Thisfurther decreases the risk of leakage of the thermal energy into thenormal bronchus thus reducing any risk of thermal injury to adjacentnormal tissue.

In one embodiment, the positioning attachment must be separated from theablation region by a distance of greater than 0.1 mm, preferably 1 mmand more preferably 1 cm. In another embodiment, the positioningattachment can be in the ablated region as long as it does not cover asignificant surface area.

In one embodiment, there are preferably two positioning attachments. Inanother embodiment, the endoscope is used as one fixation point with onepositioning element. The positioning device is between 0.1 mm and 5 cm(preferably 1 mm to 2 cm). The distal positioning device is preferablycircular with a diameter between 0.1 mm and 10 cm, preferably 1 cm to 5cm.

In another embodiment for the ablation of a bronchial neoplasm 94, thecatheter 96 is inserted through the channel of a bronchoscope 95 intothe bronchus 91 and advanced across the bronchial neoplasm 94. Thepositioning element 98 is disc shaped having an insulated membranecovering. The positioning element 98 positions the catheter in thecenter of the bronchus 91 and the insulated membrane prevents the escapeof thermal energy or ablative agent through the opening into the normalbronchus. The ablative agent 9 is passed through the infusion port 99 ina non-circumferential pattern for uniform delivery of the ablative agentto the bronchial neoplasm 94. The predetermined length “l” of theablative segment of the catheter and diameter ‘d’ of the positioningelement 98 are used to calculate the amount of thermal energy needed toablate the bronchial neoplasm 94.

FIG. 10 illustrates prostate ablation being performed on an enlargedprostrate in a male urinary system by using the device, in accordancewith an embodiment of the present invention. A cross-section of a malegenitourinary tract having an enlarged prostate 101, bladder 102, andurethra 103 is illustrated. The urethra 103 is compressed by theenlarged prostate 101. The ablation catheter 105 is passed through thecystoscope 104 positioned in the urethra 103 distal to the obstruction.The positioning elements 106 are deployed to center the catheter in theurethra 103 and insulated needles 107 are passed to pierce the prostate101. The vapor ablative agent 108 is passed through the insulatedneedles 107 thus causing ablation of the diseased prostatic tissueresulting in shrinkage of the prostate.

In one embodiment, the positioning attachment must be separated from theablation region by a distance of greater than 0.1 mm, preferably 1 mm to5 mm and no more than 2 cm. In another embodiment, the positioningattachment can be deployed in the bladder and pulled back into theurethral opening/neck of the bladder thus fixing the catheter. In oneembodiment, the positioning device is between 0.1 mm and 10 cm.

FIG. 11 illustrates fibroid ablation being performed in a female uterusby using the ablation device, in accordance with an embodiment of thepresent invention. A cross-section of a female genitourinary tractcomprising a uterine fibroid 111, uterus 112, and cervix 113 isillustrated. The ablation catheter 115 is passed through thehysteroscope 114 positioned in the uterus distal to the fibroid 111. Theablation catheter 115 has a puncturing tip 120 that helps puncture intothe fibroid 111. The positioning elements 116 are deployed to center thecatheter in the fibroid and insulated needles 117 are passed to piercethe fibroid tissue 111. The vapor ablative agent 118 is passed throughthe needles 117 thus causing ablation of the uterine fibroid 111resulting in shrinkage of the fibroid.

FIG. 12 illustrates a vapor delivery system using an RF heater forsupplying vapor to the ablation device, in accordance with an embodimentof the present invention. In an embodiment, the vapor is used as anablative agent in conjunction with the ablation device described in thepresent invention. RF heater 64 is located proximate a pressure vessel42 containing a liquid 44. RF heater 64 heats vessel 42, in turn heatingthe liquid 44. The liquid 44 heats up and begins to evaporate causing anincrease in pressure inside the vessel 42. The pressure inside vessel 42can be kept fairly constant by providing a thermal switch 46 thatcontrols resistive heater 64. Once, the temperature of the liquid 44reaches a predetermined temperature, the thermal switch 46 shuts off RFheater 64. The vapor created in pressure vessel 42 may be released via acontrol valve 50. As the vapor exits vessel 42, a pressure drop iscreated in the vessel resulting in a reduction in temperature. Thereduction of temperature is measured by thermal switch 46, and RF heater64 is turned back on to heat liquid 44. In one embodiment, the targettemperature of vessel 42 may be set to approximately 108° C., providinga continuous supply of vapor. As the vapor is released, it undergoes apressure drop, which reduces the temperature of the vapor to a range ofapproximately 90-100° C. As liquid 44 in vessel 42 evaporates and thevapor exits vessel 42, the amount of liquid 44 slowly diminishes. Thevessel 42 is optionally connected to reservoir 43 containing liquid 44via a pump 49 which can be turned on by the controller 24 upon sensing afall in pressure or temperature in vessel 42 delivering additionalliquid 44 to the vessel 42.

Vapor delivery catheter 16 is connected to vessel 42 via a fluidconnector 56. When control valve 50 is open, vessel 42 is in fluidcommunication with delivery catheter 16 via connector 56. Control switch60 may serve to turn vapor delivery on and off via actuator 48. Forexample, control switch 60 may physically open and close the valve 50,via actuator 48, to control delivery of vapor stream from the vessel 42.Switch 60 may be configured to control other attributes of the vaporsuch as direction, flow, pressure, volume, spray diameter, or otherparameters.

Instead of, or in addition to, physically controlling attributes of thevapor, switch 60 may electrically communicate with a controller 24.Controller 24 controls the RF heater 64, which in turn controlsattributes of the vapor, in response to actuation of switch 60 by theoperator. In addition, controller 24 may control valves temperature orpressure regulators associated with catheter 16 or vessel 42. A flowmeter 52 may be used to measure the flow, pressure, or volume of vapordelivery via the catheter 16. The controller 24 controls the temperatureand pressure in the vessel 42 and the time, rate, flow, volume of vaporflow through the control valve 50. These parameters are set by theoperator 11. The pressure created in vessel 42, using the targettemperature of 108° c., may be in the order of 25 pounds per square inch(psi) (1.72 bars).

FIG. 13 illustrates a vapor delivery system using a resistive heater forsupplying vapor to the ablation device, in accordance with an embodimentof the present invention. In an embodiment, the generated vapor is usedas an ablative agent in conjunction with the ablation device describedin the present invention. Resistive heater 40 is located proximate apressure vessel 42. Vessel 42 contains a liquid 44. Resistive heater 40heats vessel 42, in turn heating liquid 44. Accordingly, liquid 44 heatsand begins to evaporate. As liquid 44 begins to evaporate, the vaporinside vessel 42 causes an increase in pressure in the vessel. Thepressure in vessel 42 can be kept fairly constant by providing a thermalswitch 46 that controls resistive heater 40. When the temperature ofliquid 44 reaches a predetermined temperature, thermal switch 46 shutsoff resistive heater 40. The vapor created in pressure vessel 42 may bereleased via a control valve 50. As the vapor exits vessel 42, vessel 42experiences a pressure drop. The pressure drop of vessel 42 results in areduction of temperature. The reduction of temperature is measured bythermal switch 46, and resistive heater 40 is turned back on to heatliquid 44. In one embodiment, the target temperature of vessel 42 may beset to approximately 108° C., providing a continuous supply of vapor. Asthe vapor is released, it undergoes a pressure drop, which reduces thetemperature of the vapor to a range of approximately 90-100° C. Asliquid 44 in vessel 42 evaporates and the vapor exits vessel 42, theamount of liquid 44 slowly diminishes. The vessel 42 is connected toanother vessel 43 containing liquid 44 via a pump 49 which can be turnedon by the controller 24 upon sensing a fall in pressure or temperaturein vessel 44 delivering additional liquid 44 to the vessel 42.

Vapor delivery catheter 16 is connected to vessel 42 via a fluidconnector 56. When control valve 50 is open, vessel 42 is in fluidcommunication with delivery catheter 16 via connector 56. Control switch60 may serve to turn vapor delivery on and off via actuator 48. Forexample, control switch 60 may physically open and close the valve 50,via actuator 48, to control delivery of vapor stream from the vessel 42.Switch 60 may be configured to control other attributes of the vaporsuch as direction, flow, pressure, volume, spray diameter, or otherparameters. Instead of, or in addition to, physically controllingattributes of the vapor, switch 60 may electrically communicate with acontroller 24. Controller 24 controls the resistive heater 40, which inturn controls attributes of the vapor, in response to actuation ofswitch 60 by the operator. In addition, controller 24 may control valvestemperature or pressure regulators associated with catheter 16 or vessel42. A flow meter 52 may be used to measure the flow, pressure, or volumeof vapor delivery via the catheter 16. The controller 24 controls thetemperature and pressure in the vessel 42 as well as time, rate, flow,volume of vapor flow through the control valve 50. These parameters areset by the operator 11. The pressure created in vessel 42, using thetarget temperature of 108° C., may be on the order of 25 pounds persquare inch (psi) (1.72 bars).

The device and method of the present invention can be used to causecontrolled focal or circumferential ablation of targeted tissue tovarying depth in a manner in which complete healing withre-epithelialization can occur. The dose and manner of treatment can beadjusted based on the type of tissue and the depth of ablation needed.The ablation device can be used not only for the treatment of Barrettesophagus and esophageal dysplasia, flat colon polyps, gastrointestinalbleeding lesions, endometrial ablation, pulmonary ablation, but also forthe treatment of any mucosal, submucosal or circumferential lesion, suchas inflammatory lesions, tumors, polyps and vascular lesions. Theablation device can also be used for the treatment of focal orcircumferential mucosal or submucosal lesion of any hollow organ orhollow body passage in the body. The hollow organ can be one ofgastrointestinal tract, pancreaticobiliary tract, genitourinary tract,respiratory tract or a vascular structure such as blood vessels. Theablation device can be placed endoscopically, radiologically, surgicallyor under direct visualization. In various embodiments, wirelessendoscopes or single fiber endoscopes can be incorporated as a part ofthe device.

While the exemplary embodiments of the present invention are describedand illustrated herein, it will be appreciated that they are merelyillustrative. It will be understood by those skilled in the art thatvarious changes in form and detail may be made therein without departingfrom or offending the spirit and scope of the invention.

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 21. A method of ablating esophageal tissue comprising thesteps of: providing an ablation device comprising: a catheter having ahollow shaft through which an ablative agent can travel; at least onefirst positioning element attached to said catheter; at least oneinfusion port on said catheter for the delivery of said ablative agentto said esophageal tissue; and a controller comprising a microprocessorfor controlling the delivery of said ablative agent; inserting saidcatheter into an upper gastrointestinal tract of a patient; deployingsaid at least one first positioning element in an esophagus or a gastriccardia of said patient such that said positioning element abuts agastroesophageal structure of said patient and said catheter and said atleast one infusion port are positioned within an esophagus of saidpatient; and delivering said ablative agent through said at least oneinfusion port to ablate said esophageal tissue.
 22. The method of claim21, wherein said ablation device further comprises at least one sensorfor measuring at least one dimension of said esophagus and said methodfurther comprises the steps of: operating said at least one sensor tomeasure at least one dimension of said esophagus; and using said atleast one dimension measurement to determine the amount of ablativeagent to deliver to said esophageal tissue.
 23. The method of claim 22,wherein said at least one sensor comprises an infrared, electromagnetic,acoustic, or radiofrequency energy emitter and sensor.
 24. The method ofclaim 21, wherein said ablation device further comprises at least onesecond positioning element, attached to said catheter at a positiondifferent from said at least one first positioning element, furtherwherein a distance between said at least one first positioning elementand said at least one second positioning element is substantially equalto a length of said esophageal tissue to be ablated, and said methodfurther comprises the step of deploying said at least one secondpositioning element in said esophagus or gastric cardia to assist inpositioning said catheter within said esophagus.
 25. The method of claim21, wherein said at least one first positioning element is any one of aninflatable balloon, a wire mesh disc, a cone shaped attachment, a ringshaped attachment, or a freeform attachment configured to fit withinsaid esophagus or gastric cardia, further wherein said at least onefirst positioning element is covered by an insulated membrane to preventthe escape of ablative agent beyond said esophageal tissue to beablated.
 26. The method of claim 21, wherein said at least one firstpositioning element has a size in a range of 10 to 100 mm.
 27. Themethod of claim 21, wherein said at least one first positioning elementis separated from esophageal tissue to be ablated by a distance ofgreater than 1 mm.
 28. The method of claim 21, wherein said delivery ofsaid ablative agent is guided by predetermined programmaticinstructions.
 29. The method of claim 21, wherein a temperature of saidablative agent is in a range of −95 to 110 degrees Celsius.
 30. Themethod of claim 29, wherein said temperature is achieved in less than 1minute and maintained for up to 10 minutes.
 31. The method of claim 21,wherein esophageal pressure during ablation is no more than 5 atm. 32.The method of claim 21, wherein said ablation device further comprisesat least one sensor for measuring a parameter of said esophagus and saidmethod further comprises the steps of: operating said at least onesensor to measure a parameter of said esophagus; and using saidparameter measurement to increase or decrease a flow of said ablativeagent to said esophageal tissue.
 33. The method of claim 32, whereinsaid sensor is any one of a temperature, pressure, photo, or chemicalsensor.
 34. The method of claim 21, further comprising the step ofaffixing said catheter to an anatomical structure not being subjected toablation prior to said delivery of said ablative agent.
 35. The methodof claim 21, wherein said ablation device further comprises a coaxialmember configured to restrain said at least one first positioningelement and said step of deploying said at least one first positioningelement further comprises removing said coaxial member from saidablation device.
 36. The method of claim 21, wherein said catheterfurther comprises at least one suction port and said method furthercomprises operating said at least one suction port to remove saidablative agent from said esophagus.
 37. The method of claim 21, whereinsaid ablation device further comprises at least one input port on saidcatheter for receiving said ablative agent.
 38. The method of claim 21,wherein said ablation device further comprises an input device and saidmethod further comprises the step of an operator using said input deviceto control the delivery of said ablative agent.
 39. A method of ablatingesophageal tissue comprising the steps of: providing an ablation devicecomprising: a catheter having a hollow shaft through which an ablativeagent can travel; at least one first positioning element attached tosaid catheter; at least one infusion port on said catheter for thedelivery of said ablative agent to said esophageal tissue; at least onemechanism for measuring at least one dimension of said esophagus; and acontroller comprising a microprocessor for controlling the delivery ofsaid ablative agent; inserting said catheter into an uppergastrointestinal tract of a patient; deploying said at least one firstpositioning element in an esophagus or a gastric cardia of said patientsuch that said positioning element abuts a gastroesophageal structure ofsaid patient and said catheter and said at least one infusion port arepositioned within an esophagus of said patient; operating said at leastone mechanism to measure at least one dimension of said esophagus; usingsaid at least one dimension measurement to determine the amount ofablative agent to deliver to said esophageal tissue; and delivering saidablative agent through said at least one infusion port to ablate saidesophageal tissue.
 40. A method of ablating esophageal tissue comprisingthe steps of: providing an ablation device comprising: a catheter havinga hollow shaft through which an ablative agent can travel; at least onefirst positioning element attached to said catheter; at least one secondpositioning element, attached to said catheter at a position separatefrom said at least one first positioning element, wherein a distancebetween said at least one first positioning element and said at leastone second positioning element is substantially equal to a length ofsaid esophageal tissue to be ablated; at least one infusion port on saidcatheter for the delivery of said ablative agent to said esophagealtissue; and a controller comprising a microprocessor for controlling thedelivery of said ablative agent; inserting said catheter into an uppergastrointestinal tract of a patient; deploying said at least one firstpositioning element in a gastric cardia of said patient such that saidpositioning element abuts a gastroesophageal junction of said patientand said catheter and said at least one infusion port are positionedwithin an esophagus of said patient; deploying said at least one secondpositioning element in said esophagus to assist in positioning saidcatheter within said esophagus; and delivering said ablative agentthrough said at least one infusion port to ablate said esophagealtissue.